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arm64: enable generic CPU feature modalias matching for this architecture

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This enables support for the generic CPU feature modalias implementation that
wires up optional CPU features to udev based module autoprobing.

A file <asm/cpufeature.h> is provided that maps CPU feature numbers to
elf_hwcap bits, which is the standard way on arm64 to advertise optional CPU
features both internally and to user space.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
[catalin.marinas@arm.com: removed unnecessary "!!"]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Ard Biesheuvel 2014-03-04 01:10:04 +00:00 committed by Catalin Marinas
parent 7184659bed
commit 3be1a5c4f7
2 changed files with 30 additions and 0 deletions
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1
arch/arm64/Kconfig
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@ -16,6 +16,7 @@ config ARM64
select DCACHE_WORD_ACCESS
select GENERIC_CLOCKEVENTS
select GENERIC_CLOCKEVENTS_BROADCAST if SMP
select GENERIC_CPU_AUTOPROBE
select GENERIC_IOMAP
select GENERIC_IRQ_PROBE
select GENERIC_IRQ_SHOW

29
arch/arm64/include/asm/cpufeature.h Normal file
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@ -0,0 +1,29 @@
/*
* Copyright (C) 2014 Linaro Ltd. <ard.biesheuvel@linaro.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#ifndef __ASM_CPUFEATURE_H
#define __ASM_CPUFEATURE_H
#include <asm/hwcap.h>
/*
* In the arm64 world (as in the ARM world), elf_hwcap is used both internally
* in the kernel and for user space to keep track of which optional features
* are supported by the current system. So let's map feature 'x' to HWCAP_x.
* Note that HWCAP_x constants are bit fields so we need to take the log.
*/
#define MAX_CPU_FEATURES (8 * sizeof(elf_hwcap))
#define cpu_feature(x) ilog2(HWCAP_ ## x)
static inline bool cpu_have_feature(unsigned int num)
{
return elf_hwcap & (1UL << num);
}
#endif